Caption: Discovery of Iguanodon fossil teeth. Illustration from the 1825 paper by British geologist Gideon Mantell (1790-1852) announcing his discovery of fossil teeth for a previously unknown reptile that he named Iguanodon. This is Plate 1 from 'Notice on the Iguanodon, a newly discovered fossil reptile, from the sandstone of Tilgate Forest, in Sussex' (Philosophical Transactions of the Royal Society of London, volume 115, 1825). Mantell had found these fossil teeth in September 1820. Two contemporary experts dismissed them as teeth from a hippopotamus (Cuvier) or from a giant fish (Buckland). Cuvier later retracted and noted it as from a gigantic herbivorous reptile. Mantell found the teeth resembled that of a modern iguana lizard (lower centre). In 1825, in this paper, he gave the reptile the name Iguanodon (iguana-toothed) recognising that likeness. He associated it with other material of a giant reptile from the Tilgate quarries. It was only the second dinosaur to be named (after Buckland's Megalosaurus). The term 'dinosaur' was only coined in 1841 by Owen. These specimens are now in New Zealand's Te Papa museum where Mantell's son Walter took them after his father's death. These teeth were later reclassified as Therosaurus.